A small, sterile, connecting device that enables a mechanical union between an in situ cardiac catheter [e.g., an electrophysiology (EP) diagnostic catheter] and an electrocardiograph (ECG) cable/lead for transmission of heart signals to an ECG machine. This device allows the connection of the otherwise incompatible connectors of the cardiac catheter to a standard ECG cable/lead or a cable/lead of different manufacture. This is a single-use device.